1. Field of the Invention
The present invention relates to bushings and specifically slipper bushings. Slipper bushings are a special type of bushing used mainly in automobile suspensions although they have other applications.
Typically a bushing is comprised of inner and outer concentric metal sleeves having a rubber or other elastomeric, hollow, cylindrical body disposed between the two sleeves. In a typical bushing application the outer metal sleeve is joined to a movable member and the inner sleeve to a support element. The bushing is constructed so as to permit controlled movement between the joined parts.
There are other applications in which bushings are used where relative movement between the parts joined by the bushing is not only desirable but necessary. In such applications one bushing construction which is used is commonly referred to as a slipper bushing. One such application of a slipper bushing is in the upper and lower, both front and rear, control arms of automotive suspension systems.
2. Prior Art
One type of slipper bushing currently in use comprises an inner metal, the outer surface of which is surrounded by a plastic tube, an intermediate concentric metal the inner surface of which is in contact with the plastic and a rubber insert between the inner surface of the outer metal and outer surface of the intermediate metal. Rotation occurs between the outer surface of the plastic tube and the inner surface of the intermediate metal. A bushing of this construction is difficult to fabricate and its service life may be significantly shortened because of corrosion of the surface of rotation.
A further shortcoming of such constructions is that it exhibits an unacceptably high breakaway torque.